Every time I boot it, I get the noise then the spinning circle. After about 10 seconds it just powers off. I've unplugged the cable and tried a different outlet but same result. It's a 2008 and I spent about $350 to get it fixed about 8 months ago after my last HDD failed and it was having fan/speed issues after I installed a new HDD myself. I live in Germany right now so it's expensive to get Macs fixed out here. At this point, I don't even think it's worth getting repaired. I'm thinking it's probably a faulty power supply but I just don't have the energy to take this damn thing apart again and try to fix it. Good news is I just bought a new cMBP last weekend so I was planning on selling my iMac soon. There goes about $500 but at least I didn't pass my issues on to someone else. Still sucks though.